Motorola 6864115B62-C Detailed Service Manual page 51

Controlhead GM380/1280 Troubleshooting Flow Chart
3.3 Microprocessor
1
Measure with scope
while rotating
Volume Pot
Data Signal
on J0801
Pin 5 BUS+
?
YES
Data Signal
on TP0877
SCI_RX
?
YES
Data Signal
on TP0878
SCI_TX
?
YES
Check / Replace
D0872 / R0887
NO
Radio Controller
Check / Replace
NO
R0888 / R0889
Check / Replace
NO
Check
U0871
3-9